Efficient W-Mo mixed oxide supported CaO catalyst for the production of biodiesel from high FFA waste cooking oil: Stoichiometric effect

Abstract

Biodiesel is considered as one of the most promising biofuels produced from the vegetable oils. This is due to its environmental benign and availability of variety of feedstock. It is generally produced by either esterification reaction of free fatty acid (FFA) or transesterification reaction of triglycerides, using acid or base catalysts, respectively. In this work, the solid tungsten molybdenum supported by calcium oxide catalyst (Wx-Moy/CaO 0.3≤x, 0.7≤y) was developed and used to produce biodiesel from high FFA waste cooking oil. The catalyst was synthesized using simple wet impregnation method. The stoichiometric effects of transition metal oxides loading on acid-base properties, surface area and porosity of the catalyst were studied. The catalytic activity of the catalyst for transesterification reaction increases with the increase in the tungsten molar weight ratio over Molybdenum from 0.3 to 0.7. The W0.6-Mo0.4/CaO catalyst recorded the highest biodiesel yield of 96.2% under mild reaction conditions of 15:1 methanol to oil molar ratio, 70°C reaction temperature, 2 wt.% catalyst loading and 2 h reaction time. The newly synthesized catalysts were characterised using X-Ray Diffraction (XRD), Temperature Programmed Desorption(TPD) and Vapour Pressure Scanning Electron Microscope (VPSEM).